1. Technical Field
The present invention relates to a nitride based semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
In response to reducing power consumption due to a green energy policy, an increase in power conversion efficiency has become the main focus. In power conversion, total power conversion efficiency depends on efficiency of a power switching element. Most of power elements used in the related art include a power MOSFET or IGBT using silicon, but there is a limit to increasing efficiency of an element due to a limit in a physical property of silicon.
In order to solve the limitation, as described in Korean Patent Laid-Open Publication No. 2007-0092482 (Laid-Open Published on Sep. 13, 2007), research to increase conversion efficiency by manufacturing a nitride based field effect transistor based on nitride such as GaN is in progress.
The nitride based field effect transistor has a so called high electron mobility transistor (hereinafter, referred to as a ‘HEMT’) structure. For example, the semiconductor device having the HEMT structure includes a base substrate, a nitride based semiconductor layer formed on the base substrate, a source pad and a drain pad placed on the semiconductor layer, and a gate pad placed on the semiconductor layer between the source electrode and the drain electrode. A 2-Dimensional electron gas (2DEG) used as a movement path of current in the semiconductor layer may be generated in the semiconductor device.
However, in the nitride based field effect transistor having such a structure, a pad area which is not used directly in an active region is widely formed. As a result, by parasitic capacitance generated in the pad area, a switching speed decreases or undesired leakage current is generated.